Multiple cavity container with method and apparatus for forming the same

ABSTRACT

A plastic container for liquid or the like has an open top, with exterior threads to receive a cap, opening into a main cavity defined by the wall of the container. An inward depression is formed in the wall of the container and formed with threads so that the outer wall of the main cavity forms the interior wall of a secondary cavity. A threaded cap mates with the threads formed on the secondary cavity to close the secondary cavity. The container is preferably formed by blow molding a parison or a stretched molded tube formed with an exterior thread. One of the blow mold halves includes an interiorly extending rotatable protuberance, formed with threads, which create threads on the interior of the second cavity. As the molds are retracted, the protuberance is rotated to separate from the formed threads on the wall of the secondary cavity.

REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. provisional patent application Ser. No. 60/490,797, filed Jul. 28, 2003, said application being incorporated herein in its entirety by reference.

FIELD OF THE INVENTION

This invention relates to plastic containers having a plurality of cavities and to methods of forming such containers by blow molding or stretch molding, and to unique molds for use in such molding process.

BACKGROUND OF THE INVENTION

Containers having multiple compartments or cavities for packaging a plurality of different materials, such as liquids, powders, creams, and the like, have been proposed and have a variety of uses. Additionally, one of the compartments may contain articles such as a prize, or the like. Typically, such containers have a primary cavity and a smaller, secondary cavity containing some substance or product which is useful in connection with the liquid or other material stored in the primary cavity.

As an example, U.S. Patent Application Publication No. 2002/0008116 discloses a liquid container with a secondary compartment for retaining a supplement, such as a vitamin, mineral, analgesic, antibiotic, or other medicine, flavor, or other color additive or nutritional substance, which is useful in connection with the liquid contained in the primary container. Often, the secondary cavity of the container will include some additive which is intended to be mixed with the liquid in the primary container when the liquid is poured out of the container. U.S. Pat. No. 5,215,214 discloses a multi-compartment container of that type. U.S. Pat. No. 5,992,677 discloses a container adapted to store a liquid in the primary compartment and an article or prize in the secondary compartment. Certain containers are adapted to store products used for laundering, such as a detergent solution in the primary container and a bleach in the secondary container as disclosed in U.S. Pat. No. 4,618,444. U.S. Pat. No. 3,658,204 discloses a container for a two-component varnish, such as a urethane, wherein the components must be mixed shortly before use. Other uses of a plural cavity container might be to store a relatively large volume of face lotion or body lotion and a relatively expensive cream that is to be used only on a portion of the body, such as the eyes, in the secondary container.

As exemplified by the above-noted patents, these multi-cavity containers are often relatively complex, involving a substantial number of parts which must be assembled, and are accordingly rather expensive. One of the least expensive and most useful methods of forming liquid containers is blow molding, wherein a parison is first extruded and is then disposed in a two-part mold. Gas is injected into the interior of the parison, causing the formation of a central cavity which presses the walls of the parison against the opposed surfaces of the two mold halves to form a finished container. The economy and efficiency of this process has led to its wide scale adoption for the formation of plastic containers for liquids.

SUMMARY OF THE INVENTION

The present invention is accordingly directed toward a unique multi-cavity container which is adapted to formation by blow molding or its related variant, stretch molding. The invention is further directed toward unique process and apparatus for blow molding and stretch molding capable of forming the multi-cavity containers in a precise and economical manner.

The novel containers of the present invention are characterized by an exterior wall enclosing a main cavity and open at one end to form a spout through which the main cavity may be filled and the contents thereof may be poured out. This open top typically has threads formed about its exterior, to receive a closing cap having mating threads on its interior walls. The container further comprises one or more secondary cavities. Each secondary cavity in the container, comprises a depression formed in the exterior wall of the container such that the exterior wall in the region of the depression forms the interior walls of the respective secondary cavity. Female threads are formed about the periphery of the edge of each secondary cavity and each secondary cavity may be closed by a cap member which has male threads which engage the female threads to close off the cavity.

Any number of the secondary cavities may be formed about the exterior wall of the container. The secondary cavities are typically formed with central axes at right angles to the central axis of the main cavity, so that the cap for the main cavity is oriented at 90 degrees to the caps for the secondary cavities, but this relation is not critical.

The secondary cavity may alternatively be formed with engagement for a snap-on lid rather than a screw cap.

In the process of forming the novel containers of the present invention, by blow molding, or its variant, stretch molding, novel tooling is employed wherein the blow molding forms threads on the pour spout for the main cavity in a normal manner by pressing the surface of the parison against threaded sections formed on the two die halves. Each secondary cavity is formed by a respective male protrusion that extends inwardly, toward the opposing die half, from one of the side walls of a die half. The protrusion forms an indentation in the exterior wall of the parison as it blows out to form the interior wall of the secondary cavity. The protuberance contains formations on its outer surface, which form female threads on the wall of the second cavity where it joins the main surface of the exterior wall of the main cavity, i.e. at the entrance to the second cavity. The engagement of the threaded formation on the protuberance and the female threads thus formed at the wall of the secondary cavity prevent the. protuberance from withdrawing axially from the completed container section. Accordingly, the protuberance is rotated so as to free its threads from the molded threads in the container wall as the mold halves separate to release a molded container.

The formation of female threads in the wall of the secondary cavity by blow molding is an important aspect to the present invention. The interior walls of blow molded bottles are necessarily of indeterminate dimension because of variations in thickness of the wall of the blow molded product. By forming the exterior threads on the exterior wall of the blow molded cavity, which forms an interior wall of the secondary cavity, high quality, precision threading is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages and applications of the present invention will be made apparent by the following descriptions of preferred embodiments of the invention. The description makes reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a dual cavity container and a dispensing top for the main cavity and a cap for the secondary cavity, in exploded view;

FIG. 2A is a schematic diagram illustrating the first step in the manufacture of the container of the present invention by blow molding, wherein a parison is disposed between the two halves of an open mold, shown in cross section, built in accordance with the present invention;

FIG. 2B is the second stage of the blow molding process wherein the mold is closed on the parison and gas is introduced to the interior of the parison, forcing one of the parison walls against a rotatable protuberance on the mold;

FIG. 2C is the third stage of the process wherein the parison is continued to expand within the cavity of the mold;

FIG. 2D is the next stage of the process wherein the gas pressure on the interior walls of the parison has forced it into conformity with the walls of the mold and the protuberance;

FIG. 2E illustrates the release of the mold from the completed container;

FIG. 2F illustrates the completed container of FIG. 1 in cross section;

FIG. 3A is a view, partly perspective and partly in cross section, illustrating an alternative embodiment of the multiple cavity container of the present invention wherein the threads on the secondary cavity are formed on the exterior wall of the cavity;

FIG. 3B illustrates is a modified protrusion for the die half used to form the secondary cavity and threads of FIG. 3A.

FIG. 4A is a cross-sectional view of an alternative embodiment of the multi- cavity invention with a snap-on lid;

FIG. 4B is a front view of the snap-on lid container of FIG. 4B;

FIG. 5 is a front view of an alternative embodiment of the container having a rectangular opening in the secondary container and a fitting snap-on lid;

FIG. 6 is an alternative embodiment of the multi-cavity container of the present invention with a triangular opening to the secondary cavity and a snap-on lid;

FIG. 7 is an alternative embodiment of the present invention wherein an ornate cap for a container, in the form of a human head, is formed by the blow molding process of the present invention;

FIG. 8 is an exploded view of an alternative embodiment of the invention wherein a blow molded cap adapted to receive a straw is formed by the process of the present invention;

FIG. 9 is an exploded view of a two-cavity container formed in accordance with the present invention having a pump top;

FIG. 10 is a perspective view of an alternative embodiment of a container formed in accordance with the present invention wherein a cap blow molded in accordance with the process of the present invention is formed with a secondary cavity therein;

FIG. 11A is an exploded perspective view of an alternative embodiment of the invention constituting a three-cavity container wherein the cap for the secondary cavity is formed with its own internal third cavity;

FIG. 11B shows the embodiment of FIG. 11A assembled;

FIG. 12A is an exploded perspective view of an alternative embodiment of a squeeze bottle formed in accordance with the present invention;

FIG. 12B is a rear view of the squeeze bottle of FIG. 12A;

FIG. 12C is a cross-sectional view of the bottle of FIG. 12B, taken along line 12C-12C of FIG. 12B; and

FIG. 13 is a perspective view of a stretch tube that may be used as an alternative to the parison in blow molding certain of the containers of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, a typical multi-cavity container formed in accordance with the present invention is illustrated in FIG. 1 in exploded form with its cap. A vertical cross section through the container is illustrated in FIG. 2F.

The container, generally indicated at 10, has an open top 12 surrounded by an annular spout 14. Threads 16 are formed about the outer periphery of the spout 14. The top 12 opens into a primary container volume 18 enclosed by front and rear side walls 20 and 22, and a bottom wall 24 as well as side walls 26 connecting the front, rear and bottom walls.

The annular spout 14 may be closed off with a pouring spout 28, shown in exploded relation, which has threads on its interior cap (not shown) which mate with the threads 16 to close off the top 12. The front wall 20 of the container is formed with a central, cylindrical, inwardly directed depression 30 which forms the wall of a secondary cavity. Threads 32 are formed on the wall of the depression 30, bounding the front surface 20 of the container. This opening may be closed off with a cap 34 having a reduced diameter section 36 with threads 38 formed about its surface. The threads 38 engage with the threads 32 to retain the cap 34 at the opening of the secondary cavity formed by the depression 30. A shoulder 40 formed on the cap 34 at the margin of the reduced diameter section 32 bears against the outer surface of the wall 20 surrounding the recess 30 to seal the contents in the container.

The method of forming the container 10 by blow molding is generally illustrated in FIGS. 2A-2F. The process starts with a parison 50 (or alternatively, an injection molded stretch tube as illustrated in FIG. 13) constituting an open ended cylinder formed of a thermoformable plastic, typically produced by an extrusion process. A pair of molding die halves 52 and 54 are disposed in a conventional blow molding machine (not shown) which brings them into contact with the heated parison 50 as illustrated in FIG. 2B, so as to seal the opposed edges at one end of the cylinder 50 and bring the opposed surfaces into close proximity to one another at the other end of the cylinder, allowing a passage for the introduction of pressurized gas into the resulting envelope. As illustrated in FIG. 2B, the die half 54 includes a rotatable protrusion 56 having threads 58 formed about its outer surface beyond the point where the protrusion extends beyond the wall of the die half 54 into the interior of the mold.

As shown in FIG. 2C, gas introduced into the heated parison envelope through the passage causes the parison walls to balloon outwardly toward the dies, bringing one of the walls into contact with the surface of the protrusion 56. Continued introduction of gas causes the parison walls to form intimate contact with the mating walls of the two die halves and surround the section of the protrusion 56 which extends interiorly of the die wall 54. This forms threads 60 on the interior wall of the depression formed by the protrusion 56 engaging the parison threads 58. As has been noted, this formation of threads on the exterior wall of the blow molded product results in extremely precise thread configuration.

After the parison cools, the molding machine draws the die halves 52 and 54 away from one another. During this process it is necessary to rotate the protrusion 56 about its central axis so as to unscrew the threads 58 formed on the outer surface of the protrusion from the molded threads 60 formed by the protrusion threads in the parison 50. As illustrated in FIG. 2E, the body includes flash sections 62 and 64 extending from its top and bottom edges as a result of the capture of the parison edges in the closed mold halves. This flash is then trimmed to produce the completed bottle 10 illustrated in FIG. 2F. In addition to the main cavity 18, the bottle has a secondary cavity 66 which may be closed by the cap 34.

FIG. 3A illustrates a second embodiment of the multiple cavity container of the present invention, generally indicated at 70, which is substantially identical to the container 10 with the exception of the fact that threads 72 for closing a secondary cavity 74 are formed on the exterior sides of an annular flange 76 formed about the outer wall of the secondary cavity. FIG. 3B illustrates a modified form of the protrusion for the die half, generally indicated at 80, which is used to form the threads 72 and the annular extension 76.

FIGS. 4A and 4B respectively illustrate a cross-sectional side view and a front view of an alternative form of the multi-cavity container wherein the container is closed by a snap-on lid 90, rather than a screw cap. The snap-on lid engages circular tab section 92 formed at the outside of the secondary cavity 94. The main cavity, like the previous embodiments, is located at 96.

FIG. 5A illustrates an embodiment of the container wherein a snap-on cap 100 is generally rectangular. In the embodiment of FIG. 6 a triangular snap-on cap 102 is employed.

FIG. 7 discloses another embodiment of the invention wherein a primary container, generally indicated at 110, of a conventional variety, with a pouring spout 112 with external threads 114, is formed by conventional means such as blow molding. The secondary cavity for the container is disposed within a cap, generally indicated at 116, formed in accordance with the method of the present invention. The cap 116 is generally spherical in shape, but has an indentation 118, extending from one surface, which is formed with threads 120 on its internal wall. The cap 116 also has a pouring spout 122 which communicates with a central cavity formed on the interior of the cap so that the volume within the cap can act as a secondary cavity, relative to the main cavity, disposed in the container 110. The spout 122 may be formed with threads and may be closed off with an appropriate cap (not shown).

The cap 116 has an outer contour which is figurative, in this case representing a human face 130, with a nose and the like. Cap 130 may be formed by the blow molding process illustrated in FIGS. 2A-2E to create a hollow product with internal threads. In alternative embodiments, the cap 116 might not have a spout 122, but could simply be totally enclosed.

FIG. 8 illustrates an alternative form of cap for a container 110 which is similar to primary container illustrated in FIG. 7. A cap, generally indicated at 140, for closing off a spout on the container 110, is generally spherical and has a central recess 142 extending from one side. The recess is formed with threads 144 on its interior wall. The cap 140 has another funnel-shaped recess 146 extending from a diametrically opposite point on the cap to the opening 142. This funnel-shaped recess 146 terminates in a thin plastic wall 148, which separates the funnel 146 from the bottom of the recess 142. When the cap 140 is retained on the bottle 110, the funnel and the thin wall 148 allow the insertion of a straw into the bottle by punching through the wall 148, either with a straw itself or with another implement, so as to communicate the funnel 146 to the opening 142, and thus to the contents of the container 110. The cap 140 could be formed with its own spout communicating with a void formed in the interior of the cap to provide a secondary cavity within the cap. This, for example, might contain flavoring for the contents of the primary cavity of the container 110.

FIG. 9 illustrates a container generally indicated at 150 which corresponds to the present invention and may be formed by the method of the present invention. It includes a spout 152 with blow molded threads 154 surrounding its exterior, which communicates with a main cavity 154 within the container. A secondary cavity is formed by a depression 156 formed inwardly from the front face of the container 150. Threads 158 formed about a flange 160 allow the access to the secondary container and allow it to be closed off by cap 162.

The main cavity 154 is preferably closed off by a pump top 164 which has threads (not shown), which engage with the threads 151.

The container 150 and its top 164 might contain face lotion or body lotion, or the like, in the main cavity 154, with a more expensive body care product, such as an eye care product, in the smaller, secondary cavity 156.

Another embodiment of the invention is illustrated in FIG. 10 wherein a container, generally indicated at 180, having a threaded spout 182 and containing a main cavity, is formed by a conventional blow molding process.

The cap for the container 180 is generally indicated at 184 and constitutes a toroidal body, having threads 186 formed on its interior wall by a blow molding process of the type disclosed in FIGS. 2A-2E, so as to form an interior secondary cavity 188 within the toroidal cover. A spout 190 formed with threads 192 provides access to the secondary cavity 188 and may be closed off by an appropriate cover (not shown).

FIG. 11A discloses another embodiment of the invention wherein a blow molded container generally indicated at 200 and formed by the process of FIGS. 2A-2E, has a main cavity 202 formed as a central depression in the outer wall of the container 200, with threads 204 formed about the secondary cavity. A spout 206 formed with external threads 208 provides access to the main cavity.

The cap for closing off the secondary cavity 202, generally indicated at 210, is itself a blow molded container. The cap 210 is disc-shaped, with a hollow interior. Threads 212 are formed about its outer perimeter and a spout 214 formed with exterior threads 260 allows access to the interior of the cap 210 and may be closed off with a threaded cap 218. This forms a three cavity container, shown in FIG. 11B. The cap 210 for the secondary cavity 202 could be filled with a suitable liquid and frozen and then screwed into the bottle 200 to keep the contents of the bottle cold. Alternatively, a first liquid, such as a body lotion, could be retained in the primary cavity of the bottle 200, a second, typically more expensive lotion or material, such as eye lotion, could be retained in the secondary cavity 202, and yet a third liquid, such as hair liquid, could be retained in the third cavity, within the cap 210.

Another embodiment of the invention, constituting a squeeze container, generally indicated at 230, is shown in side-perspective view in FIG. 12A and in rear view in FIG. 12B. FIG. 12C constitutes a cross-section through the body taken along line 12C-12C of FIG. 12B.

The bottle 230, which is preferably formed by the method illustrated in FIGS. 2A-2E, has an interior main cavity 232. Access to the cavity 232 is through a spout 234 having screw threads 236 formed about its exterior. The spout 234 could be closed off with a cap 238 having a pouring aperture 240 which is hingedly retained in the cap 238 and may be moved between the open position as shown in FIG. 12A and a closed position shown in FIG. 12B. A squeeze top of this type is conventional. The bottle 230 has a secondary cavity 242 formed by an inward depression from its front side and having threads 244 arrayed about the interior wall of the depression adjacent the front face. Similarly, a third cavity 246 is formed in the front face above the cavity 242 and formed with screw threads 248. Each of them may be closed by an appropriate cap (not shown).

The rear of the container is formed with a series of corrugated louvers 250 which take the form of concentric rings. The center section 252, in the middle of the louvers 250, may be depressed by means of spots 254, to decrease the volume of the container 230 and force contents out of the spout 234.

FIG. 13 discloses a stretch molded tube, generally indicated at 280, which may be substituted for the parison 50 illustrated in FIGS. 2A-2E. The tube 280 is injection molded so as to have a central cavity 282 opening through a top 284 which has screw threads 286 formed by the injection molding process. The body 288 of the tube may be heated and used in a blow molding process in the same way as the parison 50, but the finished product will contain the previously molded cap 284 and threads 286. 

1. A multi-cavity container having an outer wall and bottom and an open top, communicating with a main cavity defined by the wall and bottom; a secondary cavity formed by a depression in the outer wall extending inwardly toward the center of the main cavity; screw threads formed about the perimeter of the depression adjacent the outer wall of the container, and caps adapted to close off the main cavity and the secondary cavity.
 2. The container of claim 1 wherein the depression in the side wall of the container forming the secondary cavity is cylindrical.
 3. The container of claim 1 which is formed by a blow molding process which also forms threads about the perimeter of the depression forming the secondary cavity.
 4. The container of claim 3 formed by a pair of mold halves including one mold half which has an inwardly extending protrusion rotatably supported within the wall of the mold half, thread producing formations on the sides of the protrusion within the die half, and means for rotating the protrusion relative to the mold half as it is withdrawn from the finished product, so as to release threads formed on the interior of the depression forming the secondary cavity from the thread-producing formations on the exterior of the protrusion.
 5. The container of claim 1 including a plurality of depressions in the outer wall forming second and subsequent secondary cavities
 6. The method of forming a blow molded, multi-cavity container, having a side wall defining a main cavity, an inwardly directed depression in the side wall defining an interior wall of a secondary cavity, and threads formed about the perimeter of said depression adjacent to the container side wall, comprising: disposing a parison between two halves of an open mold, one half having a cylindrical member rotatably supported in the mold wall and extending into the mold cavity and containing projections on its outer surface capable of forming threads; closing the mold and introducing gas to the interior of the parison to expand the parison against the mold to form a container having a central cavity and a depression formed by the cylindrical member; and rotating the cylindrical member as the mold halves are opened to release the cylindrical member from threads formed on the interior of the depression on the side wall of the resulting container.
 7. A blow molding tooling for forming a container having a main cavity enclosed by an outer wall and at least one threaded secondary cavity formed by a depression in the outer wall and extending inwardly toward the center of the main cavity, said tooling including one mold half which has an inwardly extending protrusion rotatably supported within the wall of the mold half to form said depression, and thread-producing formations on an exterior surface of the protrusion within the mold half, said tooling further comprising means for rotating the protrusion relative to the mold half as the mold half is withdrawn from the finished product, so as to release threads formed on the interior of the depression forming the secondary cavity from the thread-producing formations on the exterior of the protrusion. 